The present invention is directed to a paper stacker for receiving an endless paper web having prearranged longitudinally spaced laterally extending crease lines from a supply device such as a printer and laying the web down in a folded fashion at said crease lines to form a vertical paper stack on a stationary surface. The stacker includes a piling device for depositing the paper in a folded fashion in the stack on the stationary surface, a guide arrangement for receiving the paper from the supply device and guiding the web of paper to the piling device and a lifting arrangement including a drive motor for elevating the piling device as the height of the stack increases with the guide arrangement including guide members having a changeable length in response to movement of the pile device relative to the stationary surface.
A paper stacker, which has a piling device, a lifting arrangement for the piling device and a guide arrangement extending between the piling device and the source of paper such as a printer, are generally known and have been successfully employed. A paper stacker for a prefolded or precreased continuous form web is disclosed in U.S. Pat. No. 4,474,567 which claims priority from German OS No. 31 15 111. The U.S. patent discloses a paper stacker in which the paper deposit surface is stationary and the piling device or means together with a folding device is moved away from the stationary surface as the height of the paper stack increases. A paper guide arrangement, which has a channel that is formed by members whose lengths vary as the working height of the pile means changes, are provided between a paper feed or paper source and the pile means in order to prevent lateral excursion of the paper web while traveling therebetween. The paper guide channel can be designed as a collapsible and expandable guide channel which is independent of the movement of the deposit means.
When stacks of a continuous form have a high stack height, for example, a so-called "super pack" which has more than 3800 individual seats, are processed with such a paper stacker, an extremely great lift height is required for the pile means or device. With this great lift height, a great change in the variable length of the paper guide members and channels is required.
Paper guidance channels of this length are susceptible to malfunction and are difficult to manufacture. For example, on the one hand, they have an extreme length when a low stack is present and this will lead to disruption of the paper transport within the paper guidance channel or guide means. On the other hand, space problems can occur given paper stacks of a great height as a consequence of the telescopic paper guidance channels.